1. Field of the Invention
The present invention relates to a control apparatus for an internal combustion type electric locomotive that is suitable to a Diesel-electric locomotive using an induction motor, which is driven by a variable-voltage and variable-frequency inverter, as a motor for promoting rolling stocks.
2. Description of Related Art
A Diesel-electric locomotive is driven by transforming Diesel engine power into three-phase AC power, converting the three-phase AC power into DC power with a three-phase diode rectifier, further converting the DC power again into AC power with a variable-voltage and variable-frequency inverter, and supplying the AC power to an induction motor for promoting rolling stocks.
A Diesel engine power is determined by an engine speed determined by a notch command in a master controller, and an optimum power exists every notch. Therefore, it is necessary to control an output power of the induction motor for promotion, which is a load of the engine, according to the optimum engine power so that the output power of the induction motor for promotion may always become the engine power or less. If the load to the engine power becomes an overload, the engine may go into a stall in the worst case.
Then, methods for performing cooperative control between engine power and a load thereof have been studied up to now. As an example of this cooperative control method, there is the method disclosed in Japanese Patent Laid-Open No. 6-98412. FIG. 9 shows a block diagram of a conventional control apparatus for a Diesel-electric locomotive that performs the cooperative control.
In the figure, a master controller 1 outputs a notch signal N. A function generator 2 generates a function output Pn corresponding to predetermined engine power with an engine speed signal n as a variable. On the other hand, a function generator 3 generates a function output PN corresponding to the predetermined engine power with a notch signal N of the master controller 1 as a variable.
A low-order-preferential selector 4 inputs the function output Pn from the function generator 2 and the function output PN from the function generator 3, and selects and outputs a smaller function output. A comparator 5 corrects the output of the low-order-preferential selector 4 with a load adjustment signal outputted from an engine governor.
A constant-power pattern generator 6 generates a current pattern Ip with a rotor frequency fr of a motor for promotion as a variable and with a signal Pp, which is supplied from the comparator 5 corresponding to the engine speed signal n or the notch signal N of the master controller 1, as a parameter. This current pattern Ip becomes a current pattern of an inverter controller controlling driving of the motor for promotion.
Since the conventional apparatus has such a construction, the function output PN immediately becomes a value after the notch signal changing, when the notch signal N of the master controller 1 is increased (notch-up), that is, the engine speed and engine power are increased. Nevertheless, since there exists response time for engine control until the engine speed becomes a speed after the notch signal changing, the function output Pn determined by the engine speed becomes smaller than the function output PN determined by the notch signal. Therefore, the function output Pn is selected as an output of the low-order-preferential selector 4, and hence an overload to the engine is avoided.
On the contrary, when the notch signal of the master controller 1 is decreased (notch-down), that is, the engine speed and engine power are decreased, the function output PN immediately becomes a value after the notch signal changing. Nevertheless, since there is the response time for engine control until the engine speed becomes a speed after the notch signal changing, the function output Pn determined by the engine speed becomes larger than the function output PN determined by the notch signal. Therefore, the function output PN is selected as the output of the low-order-preferential selector 4. In addition, at the time of notch-down, neither the function output Pn nor the function output PN generates the state of the overload to the engine. Therefore, although any one can be selected, this example selects the function output PN.
As described above, a control apparatus for a Diesel-electric locomotive in conventional art realizes the cooperative control with engine power. Nevertheless, there is a problem that, since a change of power for auxiliary equipment such as a battery charger, an air compressor, and a cooling blower is not considered, the controller in the conventional art is not always in the optimum operation state for an engine.